Brake operating mechanism



Sept. 12, 1933.

W. L. KRIEG BRAKE OPERATING MECHANISM Filed Feb. 23, 1929 1K L R E my A B W ATTORNEY Patented Sept. 12, 1933 BRAKE OPERATING MECHANISM Walter L. Krieg, South Bend, Ind., assignor to Bendix Brake Company, South Bend, Ind., a

corporation of Illinois I Application February 23, 1929.

3 Claims.

This invention relates to operating mechanism for brakes and the like, and is illustrated as embodied in novel air-brake operating mechanism. An objectof the invention is to provide simple mechanism of this character in which there is a reaction on the pedal, or an equivalent operating member, which is directly in proportion to the power applied, so that the driver may feel the brakes.

In one desirable arrangement a valve or other controlling device is connected to novel means, such as a balance bar operated by the pedal, which is also directly mechanically connected to the same connections as the power device. The parts are so arranged that the power transmitted through the mechanical connections is always a definite fraction of the power supplied by said device. There is the additional advantage in this arangement that the brakescan be applied entirely by foot power in case of failure of the power device.

The above and other objects and features of the invention, including various novel and desirable details of construction, will be apparent v from the following description of theillustrative embodiment shown in the accompanying drawing, in which:

Figure 1 is a vertical section longitudinally of the car, through the novel operating mechanism;

Figure 2 is a partial section on the line 2-2 of Figure 1, showing one of the levers and its con nections, and

Figure 3 is a partial section lengthwise through the balance bar, on the line 3-3 of Figure 1.

In the arrangement illustrated, the brake pedal 10 or an equivalent operating member, is arranged to operate both mechanically and by controlled air pressure a lever 12 fulcrumed at 14 between its ends on a member 16 of the chassis frame, the lever 12 being connected to the brakes by suitable pull-rods 18 or the like.

The lower end of lever 14 is pivoted to a connecting rod 20 pivotally connected to a piston 22 in a power cylinder 24, the piston and cylinder forming part of a novel fluid power device controlled by a novel valve connected to the pedal 10. The device is intended to be operated by air compressed in any desired manner, at super-atmospheric pressure, and from any suitable source indicated diagrammatically as a tank 26.

Air from tank 26 passes, by means of a conduit 28-to a chamber 30 in the valve, which chamber I has at one side a port leading to the interior of the valve housing 32 and forming the intake port Serial No. 342,044

of the valve. This intake port is normally closed by a spring-pressed valve member 34 held closed with a conical portion against a conical seat formed in the above-described intake port. The interior of the valve housing 32 communicates by 63 a passage 36 with the cylinder 24.

The valve housing 32 has in one wall an outlet or exhaust port 38 normally closed by a sliding piston valve port connected to a transverse diaphragm 42 acted on at one side by the pressure inside the valve housing (which equals the pressure in cylinder 24) and acted on at the other side by the pressure of the atmosphere. The latter side of the diaphragm is also engaged by a coil compression spring 44 engaged by a plunger 46 connected to an operating arm 48.

It will be seen that swinging arm '48 to the left acts through spring 44 and diaphragm 42 to move slide valve part 40 to close the exhaust port 38, and also to engage the end of the valve member 34 and open the intake port. As the air pressure rises within the cylinder 24 and the valve housing, it gradually forces the diaphragm 42 back to the right, compressing the spring 44, until it reaches a normal or neutral position with both intake and exhaust ports closed and with the pressure of the spring 44 balanced against the pressure within, the valve housing. If the pressure on spring 44 is increased, the same operation takes place and the diaphragm balances again when there is a correspondingly increased pressure within the valve housing. If the pressure on spring 44 is relieved, the exhaust port 38 is opened by the air pressure within the valve acting on the diaphragm, until the reduced pressure on the spring, whereupon the spring closes the exhaust port again.

For operating the above-described parts in the manner desired, I prefer to provide a floating lever or balance bar 50, pivotally connected at its 95 upper end by means such as a pivot 52 to the lever 12 above its fulcrum, and having its lower end connected to arm 48 by means such as a link 54. Movement of the lower end of the balance bar or floating lever 50, in a valve-opening direction, is limited by means such as an adjustable set-screw 56 mounted on a fixed part such as a chassis frame member 58, the set-screw 56 or its equivalent serving as a fulcrum for the balance bar or lever 50 when the valve is open or when there is sufllcient pressure on arm 48 to compress the spring 44.

It will be seen that, since there are a number of return springs (of which one is shown attached no to the rod 18 in Fig. 1) reslstmg movement of lever 12 in a brake-applying direction, the initial depression of pedal 10 will swing the lower end of bar 50 against the stop 56, which then becomes a fulcrum, while further depression of the pedal causes the upper end of bar 50 to transmit brake-applying pressure directly to lever 12. The swinging of bar 50 against the stop 56 acts through link 54, arm 48, and spring 44, to open the intake valve 34, the exhaust valve 38 remaining closed.

As the air pressure builds up in cylinder 24, piston 22 is operated to act through the link or connecting rod 20 to apply power in a brake-applying direction to the lever 12, thus augmenting the power applied directly from the pedal to the upper end of lever 12. When the air pressure builds up sufliciently, spring 44 compresses, at the same time reacting on the pedal through the balance bar 50, until the intake valve 34 closes. Thus the total power applied to the brakes is at all times a predetermined multiple of the pedal pressure, and the driver can therefore feel his brakes even though he supplies only a portion of the brake-applying pressure directly, while the remainder is supplied by controlled air pressure.

While one illustrative embodiment has been describedin detail, it is not my intention to limit the scope of the invention to that particular embodiment or otherwise than by the terms of the appended claims.

I claim:

1. A brake operating mechanism comprising a fixed support, a lever fulcrumed on the support, a balance bar pivoted to one end of the lever, means for limiting the movement of the balance bar, a fluid power device, a control means therefor, means connecting the control means to the balance bar, means connecting the power device to the lever and an operating means connected to the balance bar.

2. A brake operating mechanism comprising a fixed support, a lever fulcrumed thereon, means for connecting the lever to a brake, a fluid power device, a control means therefor, an operating member, a balance bar connected to one end of the lever, means connecting the other end of the lever to the power device, means connecting the balance bar to the control means, means for limiting the movement of the balance bar and means connecting the balance bar to the operating member.

3. A brake operating mechanism comprising a fixed support, a lever fulcrumed thereon, means for connecting the lever to a brake, an operating member, a fluid power device, a control valve therefor, a balance bar connected to one end of 'the lever, means connecting the power device to the other end of the lever, means connecting the balance bar to the control means, means for limiting the movement of the balance bar and means connecting the balance bar to the operating member.

WALTER L. KRJEG. 

